This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in sit...This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in situ and ex situ X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,and transmission electron microscopy,the research unravels the complex structural and chemical evolution of MoS_(2) throughout its cycling.A key discovery is the identification of a unique Li intercalation mechanism in MoS_(2),leading to the formation of reversible Li_(2)MoS_(2) phases that contribute to the extra capacity of the MoS_(2) electrode.Density function theory calculations suggest the potential for overlithiation in MoS_(2),predicting Li5MoS_(2) as the most energetically favorable phase within the lithiation–delithiation process.Additionally,the formation of a Li-rich phase on the surface of Li_(4)MoS_(2) is considered energetically advantageous.After the first discharge,the battery system engages in two main reactions.One involves operation as a Li-sulfur battery within the carbonate electrolyte,and the other is the reversible intercalation and deintercalation of Li in Li_(2)MoS_(2).The latter reaction contributes to the extra capacity of the battery.The incorporation of reduced graphene oxide as a conductive additive in MoS_(2) electrodes notably improves their rate capability and cycling stability.展开更多
Iron-based electrodes have attracted great attention for sodium storage because of the distinct cost effectiveness.However,exploring suitable iron-based electrodes with high power density and long duration remains a b...Iron-based electrodes have attracted great attention for sodium storage because of the distinct cost effectiveness.However,exploring suitable iron-based electrodes with high power density and long duration remains a big challenge.Herein,a spray-drying strategy is adopted to construct graphene-coated Na_(2.4)Fe_(1.8)(SO_(4))_(3) nanograins in a 3D graphene microsphere network.The unique structural and compositional advantages endow these electrodes to exhibit outstanding electrochemical properties with remarkable rate performance and long cycle life.Mechanism analyses further explain the outstanding electrochemical properties from the structural aspect.展开更多
Mg-Y cast alloy shows excellent ductility(elongation to failure>15%)compared with pure Mg and commercial Mg cast alloys.By monitoring the microstructure evolution during an in situ tensile test of a Mg-2.5 wt%Y all...Mg-Y cast alloy shows excellent ductility(elongation to failure>15%)compared with pure Mg and commercial Mg cast alloys.By monitoring the microstructure evolution during an in situ tensile test of a Mg-2.5 wt%Y alloy,we identify the activation of prismatic<c>slip,which is rare in Mg.Synchrotron X-ray micro-beam Laue diffraction(μ-Laue)and transmission electron microscopy revealed the morphology of prismatic<c>slip bands and individual<c>dislocations.Density functional theory and molecular dynamics calculations indicate that solute Y can significantly reduce the stacking fault energy(SFE)along<c>direction on prismatic plane in Mg lattice and thus facilitate the nucleation of<c>dislocations during deformation.The presence of free<c>dislocations in the Mg lattice can also lead to nucleation of{10–12}twins even under unfavorable geometric conditions.展开更多
Slurry casting has been used to fabricate lithium-ion battery electrodes for decades,which involves toxic and expensive organic solvents followed by high-cost vacuum drying and electrode calendering.This work presents...Slurry casting has been used to fabricate lithium-ion battery electrodes for decades,which involves toxic and expensive organic solvents followed by high-cost vacuum drying and electrode calendering.This work presents a new manufacturing method using a nonthermal plasma to create inter-particle binding without using any polymeric binding materials,enabling solvent-free manufacturing electrodes with any electrochemistry of choice.The cold-plasma-coating technique enables fabricating electrodes with thickness(>200 pm),high mass loading(>30 mg cm^(-2)),high peel strength,and the ability to print lithium-ion batteries in an arbitrary geometry.This crosscutting,chemistry agnostic,platform technology would increase energy density,eliminate the use of solvents,vacuum drying,and calendering processes during production,and reduce manufacturing cost for current and future cell designs.Here,lithium iron phosphate and lithium cobalt oxide were used as examples to demonstrate the efficacy of the cold-plasma-coating technique.It is found that the mechanical peel strength of cold-plasma-coating-manufactured lithium iron phosphate is over an order of magnitude higher than that of slurry-casted lithium iron phosphate electrodes.Full cells assembled with a graphite anode and the cold-plasma-coating-lithium iron phosphate cathode offer highly reversible cycling performance with a capacity retention of 81.6%over 500 cycles.For the highly conductive cathode material lithium cobalt oxide,an areal capacity of 4.2 mAh cm^(-2)at 0.2 C is attained.We anticipate that this new,highly scalable manufacturing technique will redefine global lithium-ion battery manufacturing providing significantly reduced plant footprints and material costs.展开更多
Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with ...Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures.We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size(higher elasticity)is always accompanied by stronger ferromagnetism.We performed synchrotron x-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra,and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co–O–Co bond angles are straightened.Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure,which may open up new possibilities to develop multifunctional materials.展开更多
The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of...The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of FeN_(4)has an essential impact on the catalytic performance.Herein,we construct a sulfur-modified Fe-N-C catalyst with controllable local coordination environment,where the Fe is coordinated with four in-plane N and an axial external S.The external S atom affects not only the electron distribution but also the spin state of Fe in the FeN_(4)active site.The appearance of higher valence states and spin states for Fe demonstrates the increase in unpaired electrons.With the above characteristics,the adsorption and desorption of the reactants at FeN_(4)active sites are optimized,thus promoting the oxygen reduction reaction activity.This work explores the key point in electronic configuration and coordination environment tuning of FeN_(4)through S doping and provides new insight into the construction of M-N-C-based oxygen reduction reaction catalysts.展开更多
Low ductility and strength are major bottlenecks against Mg alloys’wide applications.In this work,we systematically design the composition and fabrication process for a low-alloyed Mg-Zn-Ca alloy,showing that it can ...Low ductility and strength are major bottlenecks against Mg alloys’wide applications.In this work,we systematically design the composition and fabrication process for a low-alloyed Mg-Zn-Ca alloy,showing that it can be extruded at low temperatures(~250℃)and high speeds(~2 mm/s).After the extrusion,this alloy exhibits a substantially weakened basal texture,relatively small grain size,very high tensile elongation(~30%),and good strength.The origin of the considerably improved ductility was studied using a combination of three-dimensional atom probe tomography(3D-APT),transmission electron microscopy(TEM),electron backscattered diffraction(EBSD)in conjunction with surface slip trace analysis,in-situ synchrotron X-ray diffraction,and elasto-plastic self-consistent(EPSC)modeling.Co-segregation of Zn and Ca atoms at a grain boundary is observed and associated with texture weakening and grain boundary mediated plasticity,both improving the ductility.While basal slip and prismatic slip are identified as the dominant deformation systems in the alloy,the ratio between their slip resistances is substantially reduced relative to pure Mg and most other Mg alloys,significantly contributing to the improved ductility of the alloy.This Mg-Zn-Ca alloy exhibiting excellent mechanical properties and low fabrication cost is a promising candidate for industrial productions.展开更多
The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchro...The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchrotron X-ray diffraction is able to go through the interior of sample and can be carried out with in situ environment,and thus,it can obtain more statistics information in real time comparing with traditional methods,such as electron and optical microscopies.In this study,in situ heating synchrotron X-ray diffraction was carried out to study the phase evolution in a typicalγ′phase precipitation strengthened Ni-based superalloy,Waspaloy,from 29 to 1050°C.Theγ′,γ,M_(23)C_(6)and M C phases,including their lattice parameters,misfits,dissolution behavior and thermal expansion coefficients,were mainly investigated.Theγ′phase and M_(23)C_(6)carbides appeared obvious dissolution during heating and re-precipitated when the temperature dropped to room temperature.Combining with the microscopy results,we can indicate that the dissolution of M_(23)C_(6)leads to the growth of grain andγ′phase cannot be completely dissolved for the short holding time above the solution temperature.Besides,the coefficients of thermal expansions of all the phases are calculated and fitted as polynomials.展开更多
The commercialization of nickel-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.To address these issues,surface modi...The commercialization of nickel-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.To address these issues,surface modification has been well-recognized as an effective strategy.Different from the coatings reported in literature to date,in this work,we for the first time report a sulfide coating,amorphous Li_(2)S via atomic layer deposition (ALD).Our study revealed that the conformal nano-Li_(2)S coating shows exceptional protection over the NMC811 cathodes,accounting for the dramatically boosted capacity retention from~11.6%to~71%and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge–discharge cycles.In addition,the Li_(2)S coating remarkably improved the rate capability of the NMC811 cathode.Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li_(2)S coating lie in the following aspects:(i) maintain the mechanical integrity of the NMC811 electrode:(ii) stabilize the NMC electrode/electrolyte interface:and (iii) suppress the irreversible phase transition of NMC structure.Particularly,this study also has revealed that the nano-Li_(2)S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides.In this regard,we disclosed that the Li_(2)S layer has reacted with the released O_(2) from the NMC lattices,and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion.Thus,this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries.展开更多
Here we demonstrate a theory-driven, novel dual-shell coating system of Li_(2)SrSiO_(4) and Al_(2)O_(3), achieved via a facile and scalable sol-gel technique on LiCoO_(2) electrode particles. The optimal thickness of ...Here we demonstrate a theory-driven, novel dual-shell coating system of Li_(2)SrSiO_(4) and Al_(2)O_(3), achieved via a facile and scalable sol-gel technique on LiCoO_(2) electrode particles. The optimal thickness of each coating can lead to increased specific capacity(~185 m Ah/g at 0.5 C-rate) at a cut-off potential of 4.5 V, and greater cycling stability at very high C rates(up to 10 C) in half-cells with lithium metal. The mechanism of this superior performance was investigated using a combination of X-ray and electron characterization methods. It shows that the results of this investigation can inform future studies to identify still better dual-shell coating schemes, achieved by such industrially feasible techniques, for application on similar, nickel-rich cathode materials.展开更多
Ameloblasts are specialized cells derived from the dental epithelium that produce enamel,a hierarchically structured tissue comprised of highly elongated hydroxylapatite(OHAp)crystallites.The unique function of the ep...Ameloblasts are specialized cells derived from the dental epithelium that produce enamel,a hierarchically structured tissue comprised of highly elongated hydroxylapatite(OHAp)crystallites.The unique function of the epithelial cells synthesizing crystallites and assembling them in a mechanically robust structure is not fully elucidated yet,partly due to limitations with in vitro experimental models.Herein,we demonstrate the ability to generate mineralizing dental epithelial organoids(DEOs)from adult dental epithelial stem cells(aDESCs)isolated from mouse incisor tissues.DEOs expressed ameloblast markers,could be maintained for more than five months(11 passages)in vitro in media containing modulators of Wnt,Egf,Bmp,Fgf and Notch signaling pathways,and were amenable to cryostorage.When transplanted underneath murine kidney capsules,organoids produced OHAp crystallites similar in composition,size,and shape to mineralized dental tissues,including some enamel-like elongated crystals.DEOs are thus a powerful in vitro model to study mineralization process by dental epithelium,which can pave the way to understanding amelogenesis and developing regenerative therapy of enamel.展开更多
Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of ma...Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of materials above 100 GPa,namely,X-ray diffraction(XRD),especially for lowZ materials,remains nontrivial in the ultrahigh-pressure region,even with the availability of brilliant synchrotron X-ray sources.In thiswork,we performa systematic study,choosing hydrogen(the lowest X-ray scatterer)as the subject,to understand how to better perform XRD measurements of low Z materials at multimegabar pressures.The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254GPa at room temperature[C.Ji et al.,Nature 573,558–562(2019)].Wepresent our discoveries and experienceswith regard to several aspects of thiswork,namely,diamond anvil selection,sample configuration for ultrahigh-pressure XRDstudies,XRDdiagnostics for low Z materials,and related issues in data interpretation and pressure calibration.Webelieve that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures,eventually testing structural models of metallic hydrogen.展开更多
Acute intermittent porphyria (AIP), an inherited disease of heme biosynthesis, is one of the most common type of the porphyrias. Reduced activity of the enzyme
Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual st...Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual stress according to Hookers Law. The present work focuses on the lattice strain determination of individual grains in a dual-phase stainless steel （DPSS） by means of differential-aperture X-ray micro-diffraction （DAXM）. The results show that the residual stress only takes part of the responsibility of the total measured lattice strain. In fact, the compositional variation inside the material was found to cause greater strain gradient in both ferrite （c~） and austenite （~） phases in DPSS. Therefore, quantification of compositional and residual stress effects on lattice strain was conducted in order to evaluate the true residual stress inside engineering materials.展开更多
Metal halide perovskites(MHPs)are an emerging class of semiconductors that have demonstrated their promise at various energy frontiers.Especially,perovskite-based solar cells(PSCs)are considered as a disruptive photov...Metal halide perovskites(MHPs)are an emerging class of semiconductors that have demonstrated their promise at various energy frontiers.Especially,perovskite-based solar cells(PSCs)are considered as a disruptive photovoltaic technology with their power conversion efficiency rapidly climbing to certified 25.7%[1].展开更多
Doping have been considered as a prominent strategy to stabilize crystal structure of battery materials during the insertion and removal of alkali ions.The instructive knowledge and experience acquired from doping str...Doping have been considered as a prominent strategy to stabilize crystal structure of battery materials during the insertion and removal of alkali ions.The instructive knowledge and experience acquired from doping strategies predominate in cathode materials,but doping principle in anodes remains unclear.Here,we demonstrate that trace element doping enables stable conversion-reaction and ensures structural integrity for potassium ion battery(PIB) anodes.With a synergistic combination of X-ray tomography,structural probes,and charge reconfiguration,we encode the physical origins and structural evolution of electro-chemo-mechanical degradation in PIB anodes.By the multiple ion transport pathways created by the orderly hierarchical pores from "surface to bulk" and the homogeneous charge distribution governed in doped nanodomains,the anisotropic expansion can be significantly relieved with trace isoelectronic element doping into the host lattice,maintaining particle mechanical integrity.Our work presents a close relationship between doping chemistry and mechanical reliability,projecting a new pathway to reengineering electrode materials for next-generation energy storage.展开更多
As a new class of lithium rich cathodes,disordered rock-salt cathodes have been of primary interest,because of their ability to deliver a promisingly high capacity up to 300 mAh/g.Nevertheless,some fundamental issues ...As a new class of lithium rich cathodes,disordered rock-salt cathodes have been of primary interest,because of their ability to deliver a promisingly high capacity up to 300 mAh/g.Nevertheless,some fundamental issues are yet to be fully understood and a comprehensive mastering of their solid-state chemistry,kinetics and thermal stability is required.Here,we select a high capacity cation-disordered positive electrode-Li_(1.2)Ni_(0.4)Nb_(0.4)O_(2)as a model compound to study intrinsic reaction mechanism,including charge compensation mechanism,kinetics,thermal stability,and structural evolution.By combining soft and hard X-ray absorption spectroscopy(XAS),X-ray photoelectron spectroscopy(XPS)with operando and exsitu differential scanning calorimetry(DSC),galvanostatic intermittent titration technique(GITT),cyclic voltammetry(CV),and X-ray diffraction(XRD),we present holistic information on disordered rock-salt cathode.This work provides beneficial insights into designing and tailoring new positive electrodes with disordered rock-salt structure.展开更多
A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer,which simultaneously enables the high spatial resolution imagin...A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer,which simultaneously enables the high spatial resolution imaging and the improved image contrast.By using this theory,several key parameters of phase contrast imaging can be predicted,for instance,the fringe visibility and period,and the conversion condition from the differential phase imaging(DPI)to the phase difference imaging(PDI).Additionally,numerical simulations are performed with certain x-ray optical components and imaging geometry.Comparison with the available experimental measurement[Appl.Phys.Lett.113063105(2018)]demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.展开更多
基金the financial support from the Science, Technology, and Innovation Funding Authority (STIFA, STDF previously) through project number 42691 entitled “Microstructure-Based, Multi-Physics Simulation and Optimization to Improve Battery Performance”supported by the U.S. DOE (Department of Energy), Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357supported by the U.S. DOE Vehicle Technologies office, under contract number DE-AC02-06CH11357
文摘This study investigates the electrochemical behavior of molybdenum disulfide(MoS_(2))as an anode in Li-ion batteries,focusing on the extra capacity phenomenon.Employing advanced characterization methods such as in situ and ex situ X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,and transmission electron microscopy,the research unravels the complex structural and chemical evolution of MoS_(2) throughout its cycling.A key discovery is the identification of a unique Li intercalation mechanism in MoS_(2),leading to the formation of reversible Li_(2)MoS_(2) phases that contribute to the extra capacity of the MoS_(2) electrode.Density function theory calculations suggest the potential for overlithiation in MoS_(2),predicting Li5MoS_(2) as the most energetically favorable phase within the lithiation–delithiation process.Additionally,the formation of a Li-rich phase on the surface of Li_(4)MoS_(2) is considered energetically advantageous.After the first discharge,the battery system engages in two main reactions.One involves operation as a Li-sulfur battery within the carbonate electrolyte,and the other is the reversible intercalation and deintercalation of Li in Li_(2)MoS_(2).The latter reaction contributes to the extra capacity of the battery.The incorporation of reduced graphene oxide as a conductive additive in MoS_(2) electrodes notably improves their rate capability and cycling stability.
基金financial support by the National Natural Science Foundation of China(Nos.21673165 and 21972108)National Key Research Program of China(No.2016YFB0901500)the supercomputing system in the Supercomputing Center of Wuhan University。
文摘Iron-based electrodes have attracted great attention for sodium storage because of the distinct cost effectiveness.However,exploring suitable iron-based electrodes with high power density and long duration remains a big challenge.Herein,a spray-drying strategy is adopted to construct graphene-coated Na_(2.4)Fe_(1.8)(SO_(4))_(3) nanograins in a 3D graphene microsphere network.The unique structural and compositional advantages endow these electrodes to exhibit outstanding electrochemical properties with remarkable rate performance and long cycle life.Mechanism analyses further explain the outstanding electrochemical properties from the structural aspect.
基金financially supported by the National Natural Science Foundation of China (Nos. 51671127, 51631006, 51971168)sponsored by the Shanghai Rising-Star Programsupported by the United States Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02–06CH11357
文摘Mg-Y cast alloy shows excellent ductility(elongation to failure>15%)compared with pure Mg and commercial Mg cast alloys.By monitoring the microstructure evolution during an in situ tensile test of a Mg-2.5 wt%Y alloy,we identify the activation of prismatic<c>slip,which is rare in Mg.Synchrotron X-ray micro-beam Laue diffraction(μ-Laue)and transmission electron microscopy revealed the morphology of prismatic<c>slip bands and individual<c>dislocations.Density functional theory and molecular dynamics calculations indicate that solute Y can significantly reduce the stacking fault energy(SFE)along<c>direction on prismatic plane in Mg lattice and thus facilitate the nucleation of<c>dislocations during deformation.The presence of free<c>dislocations in the Mg lattice can also lead to nucleation of{10–12}twins even under unfavorable geometric conditions.
基金the financial support from Intecells Inc.via an award number AWD_19-08-0127the support from Paul M.Rady Mechanical Engineering Department at University of Colorado Boulder
文摘Slurry casting has been used to fabricate lithium-ion battery electrodes for decades,which involves toxic and expensive organic solvents followed by high-cost vacuum drying and electrode calendering.This work presents a new manufacturing method using a nonthermal plasma to create inter-particle binding without using any polymeric binding materials,enabling solvent-free manufacturing electrodes with any electrochemistry of choice.The cold-plasma-coating technique enables fabricating electrodes with thickness(>200 pm),high mass loading(>30 mg cm^(-2)),high peel strength,and the ability to print lithium-ion batteries in an arbitrary geometry.This crosscutting,chemistry agnostic,platform technology would increase energy density,eliminate the use of solvents,vacuum drying,and calendering processes during production,and reduce manufacturing cost for current and future cell designs.Here,lithium iron phosphate and lithium cobalt oxide were used as examples to demonstrate the efficacy of the cold-plasma-coating technique.It is found that the mechanical peel strength of cold-plasma-coating-manufactured lithium iron phosphate is over an order of magnitude higher than that of slurry-casted lithium iron phosphate electrodes.Full cells assembled with a graphite anode and the cold-plasma-coating-lithium iron phosphate cathode offer highly reversible cycling performance with a capacity retention of 81.6%over 500 cycles.For the highly conductive cathode material lithium cobalt oxide,an areal capacity of 4.2 mAh cm^(-2)at 0.2 C is attained.We anticipate that this new,highly scalable manufacturing technique will redefine global lithium-ion battery manufacturing providing significantly reduced plant footprints and material costs.
基金the National Natural Science Foun-dation of China(Grant Nos.52072244 and 12104305)the Science and Technology Commission of Shanghai Municipal-ity(Grant No.21JC1405000)the ShanghaiTech Startup Fund.This research used resources of the Advanced Photon Source,a U.S.Department of Energy(DOE)Office of Sci-ence User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures.We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size(higher elasticity)is always accompanied by stronger ferromagnetism.We performed synchrotron x-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra,and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co–O–Co bond angles are straightened.Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure,which may open up new possibilities to develop multifunctional materials.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0715000)the National Natural Science Foundation of China(Grant No.52127816)+2 种基金supported by the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy,Vehicle Technologies Officethe DOE Office of Science by UChicago Argonne LLC under contract no.DE-AC02-06CH11357the Advanced Photon Source(APS),a U.S.Department of Energy(DOE)Office of Science User Facility,operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357
文摘The Fe-N-C material represents an attractive oxygen reduction reaction electrocatalyst,and the FeN_(4)moiety has been identified as a very competitive catalytic active site.Fine tuning of the coordination structure of FeN_(4)has an essential impact on the catalytic performance.Herein,we construct a sulfur-modified Fe-N-C catalyst with controllable local coordination environment,where the Fe is coordinated with four in-plane N and an axial external S.The external S atom affects not only the electron distribution but also the spin state of Fe in the FeN_(4)active site.The appearance of higher valence states and spin states for Fe demonstrates the increase in unpaired electrons.With the above characteristics,the adsorption and desorption of the reactants at FeN_(4)active sites are optimized,thus promoting the oxygen reduction reaction activity.This work explores the key point in electronic configuration and coordination environment tuning of FeN_(4)through S doping and provides new insight into the construction of M-N-C-based oxygen reduction reaction catalysts.
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0701203)the National Natural Science Foundation of China(Nos.51631006,51671127 and 51825101)+3 种基金sponsored by the Youth Cheung Kong Scholars Programthe Shanghai Rising-Star Programthe support provided by the U.S.National Science Foundation(No.OIA-1757371)Use of the Advanced Photon Source was supported by the United States Department of Energy,Office of Science,Office of Basic Energy Sciences(No.DE-AC02-06CH11357)。
文摘Low ductility and strength are major bottlenecks against Mg alloys’wide applications.In this work,we systematically design the composition and fabrication process for a low-alloyed Mg-Zn-Ca alloy,showing that it can be extruded at low temperatures(~250℃)and high speeds(~2 mm/s).After the extrusion,this alloy exhibits a substantially weakened basal texture,relatively small grain size,very high tensile elongation(~30%),and good strength.The origin of the considerably improved ductility was studied using a combination of three-dimensional atom probe tomography(3D-APT),transmission electron microscopy(TEM),electron backscattered diffraction(EBSD)in conjunction with surface slip trace analysis,in-situ synchrotron X-ray diffraction,and elasto-plastic self-consistent(EPSC)modeling.Co-segregation of Zn and Ca atoms at a grain boundary is observed and associated with texture weakening and grain boundary mediated plasticity,both improving the ductility.While basal slip and prismatic slip are identified as the dominant deformation systems in the alloy,the ratio between their slip resistances is substantially reduced relative to pure Mg and most other Mg alloys,significantly contributing to the improved ductility of the alloy.This Mg-Zn-Ca alloy exhibiting excellent mechanical properties and low fabrication cost is a promising candidate for industrial productions.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.11805009 and 51921001)the Fundamental Research Funds for the Central Universities(Grant No.06111020)。
文摘The phase evolution and thermal expansion behavior in superalloy during heating play an essential role in controlling the size and distribution of precipitates,as well as optimizing thermomechanical properties.Synchrotron X-ray diffraction is able to go through the interior of sample and can be carried out with in situ environment,and thus,it can obtain more statistics information in real time comparing with traditional methods,such as electron and optical microscopies.In this study,in situ heating synchrotron X-ray diffraction was carried out to study the phase evolution in a typicalγ′phase precipitation strengthened Ni-based superalloy,Waspaloy,from 29 to 1050°C.Theγ′,γ,M_(23)C_(6)and M C phases,including their lattice parameters,misfits,dissolution behavior and thermal expansion coefficients,were mainly investigated.Theγ′phase and M_(23)C_(6)carbides appeared obvious dissolution during heating and re-precipitated when the temperature dropped to room temperature.Combining with the microscopy results,we can indicate that the dissolution of M_(23)C_(6)leads to the growth of grain andγ′phase cannot be completely dissolved for the short holding time above the solution temperature.Besides,the coefficients of thermal expansions of all the phases are calculated and fitted as polynomials.
基金support from the Center for Advanced Surface Engineering, under the National Science Foundation Grant No. OIA-1457888the Arkansas EPSCoR Program, ASSET Ⅲ. X. M+1 种基金the financial support from the University of Arkansas, Fayetteville, AR, USAfunded by the U.S. Department of Energy (DOE), Vehicle Technologies Office。
文摘The commercialization of nickel-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.To address these issues,surface modification has been well-recognized as an effective strategy.Different from the coatings reported in literature to date,in this work,we for the first time report a sulfide coating,amorphous Li_(2)S via atomic layer deposition (ALD).Our study revealed that the conformal nano-Li_(2)S coating shows exceptional protection over the NMC811 cathodes,accounting for the dramatically boosted capacity retention from~11.6%to~71%and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge–discharge cycles.In addition,the Li_(2)S coating remarkably improved the rate capability of the NMC811 cathode.Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li_(2)S coating lie in the following aspects:(i) maintain the mechanical integrity of the NMC811 electrode:(ii) stabilize the NMC electrode/electrolyte interface:and (iii) suppress the irreversible phase transition of NMC structure.Particularly,this study also has revealed that the nano-Li_(2)S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides.In this regard,we disclosed that the Li_(2)S layer has reacted with the released O_(2) from the NMC lattices,and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion.Thus,this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries.
基金supported by the U.S. National Science Foundation (CBET-1949870, CBET-2016192, and DMR-1832803)Part of the research was conducted at the Northwest Nanotechnology Infrastructure, a National Nanotechnology Coordinated Infrastructure (NNCI) site at Oregon State University, which is supported, in part, by the U.S. National Science Foundation (NNCI-1542101 and NCC-2025489), and Oregon State University。
文摘Here we demonstrate a theory-driven, novel dual-shell coating system of Li_(2)SrSiO_(4) and Al_(2)O_(3), achieved via a facile and scalable sol-gel technique on LiCoO_(2) electrode particles. The optimal thickness of each coating can lead to increased specific capacity(~185 m Ah/g at 0.5 C-rate) at a cut-off potential of 4.5 V, and greater cycling stability at very high C rates(up to 10 C) in half-cells with lithium metal. The mechanism of this superior performance was investigated using a combination of X-ray and electron characterization methods. It shows that the results of this investigation can inform future studies to identify still better dual-shell coating schemes, achieved by such industrially feasible techniques, for application on similar, nickel-rich cathode materials.
基金supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea Government (MSIP) (NRF-2022R1A2B5B03001627)facilities operated by Northwestern University:EPIC and SPID facilities of Northwestern University’s NUANCE Center,which have received support from the SHyNE Resource (NSF ECCS-2025633)+4 种基金the IIN,and Northwestern’s MRSEC program (NSF DMR-1720139)MatCI,supported by the MRSEC program (NSF DMR-1720139) at the Materials Research Centerthe Northwestern University George M.O’Brien Kidney Research Core Center (NU GoKidney),an NIH/NIDDK funded program (P30DK114857)supported in part by NIH UH3 DE028872supported in part by the National Science Foundation through a Graduate Research Fellowship (DGE-1842165)
文摘Ameloblasts are specialized cells derived from the dental epithelium that produce enamel,a hierarchically structured tissue comprised of highly elongated hydroxylapatite(OHAp)crystallites.The unique function of the epithelial cells synthesizing crystallites and assembling them in a mechanically robust structure is not fully elucidated yet,partly due to limitations with in vitro experimental models.Herein,we demonstrate the ability to generate mineralizing dental epithelial organoids(DEOs)from adult dental epithelial stem cells(aDESCs)isolated from mouse incisor tissues.DEOs expressed ameloblast markers,could be maintained for more than five months(11 passages)in vitro in media containing modulators of Wnt,Egf,Bmp,Fgf and Notch signaling pathways,and were amenable to cryostorage.When transplanted underneath murine kidney capsules,organoids produced OHAp crystallites similar in composition,size,and shape to mineralized dental tissues,including some enamel-like elongated crystals.DEOs are thus a powerful in vitro model to study mineralization process by dental epithelium,which can pave the way to understanding amelogenesis and developing regenerative therapy of enamel.
基金This research was supported by the National Natural Science Foundation of China under Award No.U1930401the Department of Energy(DOE),Office of Basic Energy Science,Division of Materials Sciences and Engineering under Award No.DE-FG02-99ER45775
文摘Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensedmatter.However,the onlyway to determine crystal structures of materials above 100 GPa,namely,X-ray diffraction(XRD),especially for lowZ materials,remains nontrivial in the ultrahigh-pressure region,even with the availability of brilliant synchrotron X-ray sources.In thiswork,we performa systematic study,choosing hydrogen(the lowest X-ray scatterer)as the subject,to understand how to better perform XRD measurements of low Z materials at multimegabar pressures.The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254GPa at room temperature[C.Ji et al.,Nature 573,558–562(2019)].Wepresent our discoveries and experienceswith regard to several aspects of thiswork,namely,diamond anvil selection,sample configuration for ultrahigh-pressure XRDstudies,XRDdiagnostics for low Z materials,and related issues in data interpretation and pressure calibration.Webelieve that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures,eventually testing structural models of metallic hydrogen.
文摘Acute intermittent porphyria (AIP), an inherited disease of heme biosynthesis, is one of the most common type of the porphyrias. Reduced activity of the enzyme
基金financial supported by the National Science Foundation of China(No.51231002)supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-06CH11357
文摘Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual stress according to Hookers Law. The present work focuses on the lattice strain determination of individual grains in a dual-phase stainless steel （DPSS） by means of differential-aperture X-ray micro-diffraction （DAXM）. The results show that the residual stress only takes part of the responsibility of the total measured lattice strain. In fact, the compositional variation inside the material was found to cause greater strain gradient in both ferrite （c~） and austenite （~） phases in DPSS. Therefore, quantification of compositional and residual stress effects on lattice strain was conducted in order to evaluate the true residual stress inside engineering materials.
基金startup grants,Initiation Grant-Faculty Niche Research Areas(IG-FNRA)2020/21Interdisciplinary Matching Scheme 2020/21 of the Hong Kong Baptist University(HKBU)+1 种基金the Early Career Scheme(No.22300221)from the Hong Kong Research Grant Councilthe support of the Hong Kong Ph.D.Fellowship Scheme。
文摘Metal halide perovskites(MHPs)are an emerging class of semiconductors that have demonstrated their promise at various energy frontiers.Especially,perovskite-based solar cells(PSCs)are considered as a disruptive photovoltaic technology with their power conversion efficiency rapidly climbing to certified 25.7%[1].
基金supported by the start-up fund and‘‘Young Scientist Studio”of Harbin Institute of Technology(HIT)the National Natural Science Foundation of China(No.U1932205)+1 种基金the Natural Science Funds of Heilongjiang Province(No.ZD2019B001)the HIT Research Institute(Zhao Yuan)of New Materials and the Intelligent Equipment Technology Co.,Ltd.Scientific and Technological Cooperation and Development Fund(No.2017KJHZ002)。
文摘Doping have been considered as a prominent strategy to stabilize crystal structure of battery materials during the insertion and removal of alkali ions.The instructive knowledge and experience acquired from doping strategies predominate in cathode materials,but doping principle in anodes remains unclear.Here,we demonstrate that trace element doping enables stable conversion-reaction and ensures structural integrity for potassium ion battery(PIB) anodes.With a synergistic combination of X-ray tomography,structural probes,and charge reconfiguration,we encode the physical origins and structural evolution of electro-chemo-mechanical degradation in PIB anodes.By the multiple ion transport pathways created by the orderly hierarchical pores from "surface to bulk" and the homogeneous charge distribution governed in doped nanodomains,the anisotropic expansion can be significantly relieved with trace isoelectronic element doping into the host lattice,maintaining particle mechanical integrity.Our work presents a close relationship between doping chemistry and mechanical reliability,projecting a new pathway to reengineering electrode materials for next-generation energy storage.
文摘As a new class of lithium rich cathodes,disordered rock-salt cathodes have been of primary interest,because of their ability to deliver a promisingly high capacity up to 300 mAh/g.Nevertheless,some fundamental issues are yet to be fully understood and a comprehensive mastering of their solid-state chemistry,kinetics and thermal stability is required.Here,we select a high capacity cation-disordered positive electrode-Li_(1.2)Ni_(0.4)Nb_(0.4)O_(2)as a model compound to study intrinsic reaction mechanism,including charge compensation mechanism,kinetics,thermal stability,and structural evolution.By combining soft and hard X-ray absorption spectroscopy(XAS),X-ray photoelectron spectroscopy(XPS)with operando and exsitu differential scanning calorimetry(DSC),galvanostatic intermittent titration technique(GITT),cyclic voltammetry(CV),and X-ray diffraction(XRD),we present holistic information on disordered rock-salt cathode.This work provides beneficial insights into designing and tailoring new positive electrodes with disordered rock-salt structure.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12027812 and 11804356)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2021362).
文摘A general theoretical framework is presented to explain the formation of the phase signal in an x-ray microscope integrated with a grating interferometer,which simultaneously enables the high spatial resolution imaging and the improved image contrast.By using this theory,several key parameters of phase contrast imaging can be predicted,for instance,the fringe visibility and period,and the conversion condition from the differential phase imaging(DPI)to the phase difference imaging(PDI).Additionally,numerical simulations are performed with certain x-ray optical components and imaging geometry.Comparison with the available experimental measurement[Appl.Phys.Lett.113063105(2018)]demonstrates the accuracy of this developed quantitative analysis method of x-ray phase-sensitive microscope imaging.
